That's interesting because I work in industrial data and pretty much everything is stored and logged as UTC to avoid these kinds of mess ups.

  best practice for a real calendar app was to store in local time with time zone, not UTC with offset

Either UTC or TAI should be used for anything that is truly a "time".

The "time" at which future events are scheduled by humans (i.e. not the time when future events are predicted, like astronomical events), is not a "time", but it is a different data type, which must have a different name and which must store different information (i.e. legal date and time at a certain location).